The day after I flushed the cooling system, I found that the oil cooler is leaking from what appears to be a casting seam.
Pic shows some greenish corrosion where the seam has been weeping coolant for some period. There is no obvious counterpart in the inside of the housing, but it must be coming from somewhere along that seam.
Another way that this could spring a leak is if it froze. There would be a rather large cross section of water to act against the casting. I would expect it to crack along the top or bottom edge, but expanding ice expands equally in all directions and it can be difficult for a non-engineer to judge where the weak point will be. I do not see evidence of freeze damage in this casting -- it's usually easy to spot.
This casting (teal in the drawing above) is available from my dealer, about $82. Add in the two gaskets, four o-rings, and the crooked hose, and I should be able to do the whole repair for under $120 and a bunch of bolts -- if the bolts don't snap off.
[later]
Bad news. Joe@tacomanissan had said everything was available, and I told him to order it all. Today, he calls me back, says the crooked hose is available, and the two gaskets, but the o-rings and the housing aren't.
[later]
I called my "local" forklift place, and they were very helpful. It seems that the oil cooler assy. for the forklifts looks (on paper) quite a bit like the one for the trucks, though not identical. And the forklift one comes in two flavours, one pre-'80, one '80-on. They faxed me the exploded view of the later one, and the housing casting is different, but looks like it would bolt on with shorter bolts. And it's still available (the assy, not the casting alone) -- five of them in Illinois . . . for $388 each!
My oil cooler's construction matches the dealer's diagram (2nd pic from the top). Notice that the casting (ref. No. 3 in the forklift diagram) is open on both sides on the dealer's diagram, closed on the outer surface on the forklift's. The forklift version bolts the oil cooler itself (No. 2) to the closed end, via gasket No. 4 and three studs, nuts, washers.
Mine, OTOH, mounts the oil cooler directly to the steel outside cover, which bolts on to the casting and seals with two gaskets No. 7 (the forklift's needs only one gasket No. 7, it does not have an "outside" cover).
Forklift casting No. 3 is NLA separately, and even if it were, it would do me no good, as I'd have to also have an oil cooler No. 2, gasket No. 4 and three nuts/washers to mount it to the inside of casting No. 3 .
[later]
The leak is definitely at the casting seam. I took the heat exchanger off, cleaned it up, took it to our local weld-it shop, they expressed high confidence in making it water-tight again. I asked the welder to fill over both inside and outside seams all along that side of the casting.
Bolts: one of eight snapped off. Penetrant didn't help, but amazingly I didn't need to use the heat wrench. I used a Blue-Point 5/16" stud extractor and it screwed right out. Surprised the heck out of me. This style of extractor uses three or four sprag-rollers to lock onto the remains of the bolt/stud. WFM!
The big gaskets will arrive Monday, the 10.9 hardness replacement bolts arrived on Friday, and when the welder has completed waving his magic wand over the casting, muttering the appropriate spell(s), I'll start putting it back together.
I have arranged to use a lapping table tomorrow to check flatness of the welded part once I get it back, and if I've got more than about .005" warpage (welder thought that I might not, he's using TIG), I'll have it flattened by the local machine shop. I'm not equipped with a flat-enough table to even check a casting this size (I've got a real straightedge for checking solid castings, but it's nearly useless for hollow castings).
[end of story]
I had a good deal of trouble sourcing the correct o-rings, but after that hurdle, it all went back together easily, and has been running for 15 months without incident.
Free. You pay shipping.
. Let me know what I need to do on the shipping.
